Ok so this is my very first fan fiction. It may be bad and a bit OCC so I'm just throwing that out there as a warning. I don't own Undertale or any of the characters (sadly ;-;).

Genocide

Sans stood in the middle of the battle field. It was dark and cold, like everything else in the Underworld now. If he listened he could hear the wind blowing and the anguished wails of King Asgore in the next room. The human was most likely killing him in the worst ways imaginable. Sans couldn't bare to think of what was happening.

His non-existent stomach grew sick at the sight of the blood and dust of his friends all around him. It was everywhere. It was on the floor, the walls, the ceiling, and even on him. No matter how hard he wanted it all to go away, it wouldn't. He desperately wished that they were still here, still smiling, still happy, how it was before. Even if they were stuck in the Underworld like the rest of the monsters, at least they were happy. At least they had had each other.

The worst part, he thought, was that there were no corpses to differentiate his friends from. Monsters only turned to dust when they died. All the dust was mixed together, so he couldn't even try to tell them apart.

He couldn't believe that the gentle little human that stumbled down into the caves just a day or so ago could create so much destruction. Alyphys, Undyne, and even Toriel, who had only shown them kindness from the very beginning, were now dead. Everyone was gone. Everyone was dust. Like they had never even been here. The only monster alive other than Sans was Papyrus, who was currently in Sans arms, but even he would turn to dust soon.

"C'mon bro. You can't leave me. Not like everyone else. Please." Even though he didn't have eyes, tears were steadily streaming down San's face. Papyrus gave him a grim smile before coughing violently. Somehow blood was dripping from his mouth which should have been impossible if he wasn't a monster. The both of them were skeletons after all.

"I'm sorry Sans. It seems the human took down the great Papyrus. Not even I could stop them." He looked into his brother's eyes with great sorrow. "It seems I too will have to turn to dust now…"

Sans's heart broke with that single sentence. He didn't notice the kings screams stopping, and he didn't hear the door opening. All he could focus on was his brother. All he could think about was the human that caused this.

Sans's hands shook with rage. How dare they. How dare they come into the caverns and mess everything up. How dare they gain our trust and then treat us like trash. How dare they SAVE and RESET like this is just a game. How dare they play god with real lives.

Papyrus sighed "Sans I know that you're angry… but… it's not… the humans… fault. Chara possessed Frisk. You… you know this. Please just… stay determined." Sans looked at his brother in shock as he morphed into dust right in front of his eyes. He was gone.

The skeleton finally took notice of the other person in the room. They stood right in front of him with that insane grin on their face while chuckling. The human. Frisk. No, this wasn't Frisk. Frisk would never kill their friends. Frisk would never play with other people's lives. Frisk definitely wouldn't abuse their power of SAVE just to kill people. No. This was Chara. This was a murderer.

While Sans was glaring holes at the perpetrator their chuckling only grew until they were laughing hysterically on the ground with tears in their eyes. Sans finally stood up, his left eye literally burning blue fire in utter rage. His magic grew by the minute and he let a grin slip onto his face.

"You're gonna have a bad time." Sans let his magic grip onto Chara, who stopped laughing in shock, and threw them around like a ragdoll. Chara hit the walls, floor, and ceiling multiple times before Sans released them. They hit the ground hard with a groan, but Sans wasn't done yet. He whipped out his Gasterblasters out of seemingly nowhere and shot Chara multiple times with them. Charas health bar went down until it was only 1/99. This would be over soon.

Chara looked up and shakily grinned. "Looks like you got me Sans." Tears streamed down their face, but the smile stayed in place. "It was fun while it lasted that's for sure." They stood and looked to the side. Looking at the destruction they had caused.

"I'm not sorry Sans, and I'm not stupid. I'm going to die. I'll never die by your hands though. I'll RESET. For some reason I can't reach my SAVEs anyway, so I guess I'll give up for now… But mark my words Sans. I will be back, and I will kill you one of these timelines. I can promise you that." Chara picked up the knife they had brought with them and plunged it deep in their chest.

San's could only watch as they fell to the ground, lifeless.

Everything turned black. Everything was RESET.